- Author: Ed Perry
Trees normally begin to show fall colors in late October, especially after a several cold nights. If you are seeing orange, yellow, red, burgundy, and purple leaves on deciduous trees this time of year, it's a symptom of stress. You might not be able to do anything to correct the problem now, but much can be done to prevent a repeat next fall, and improve the health of your tree before spring.
First, determine the source of the stress and correct it. Look closely at the tree. Check for wounds on the trunk from mechanical injury or sunburn. If early fall color is the result of wounds, take steps to prevent further wounding. The trunks of young trees can be protected from string weeder damage with plastic sleeves. Better yet, place chip mulch on the soil around the tree to remove the temptation to mow or weed right up to the trunk.
Determine if the tree is growing in a site where the roots may be restricted by pavement or buildings. Is it possible the roots were recently cut? Root disease, recent disruption to roots from construction or grade changes, surface soil compaction from vehicles or foot traffic and girdling roots can also cause trees to develop early fall color. If surface compaction is a problem, loosen the soil by cultivating to a depth of 4 to 6 inches. This should improve moisture and oxygen penetration. Follow up by watering the tree deeply.
The best way to prevent stress and early fall color is to make sure the tree receives sufficient deep water during the summer. If you haven't already, deep water your tree. Sprinkler water does not provide adequate water for trees, so supplement with a hose, focusing the water underneath the tree canopy. For mature trees, water needs to penetrate to a depth of 12-18" to provide enough water.
For questions about your trees, contact the Master Gardeners at (209) 525-6862 or fill out this form http://ucanr.edu/ask/ucmgstanislaus
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.
- Author: Dr. Anthony Fulford
What is subsoil?
There are several layers (also known as “horizons” to soil scientists) that can be found when we dig deeper and deeper down into the soil. We can imagine all the individual layers of a soil stacked one on top of the other like a layer cake, this is called the soil profile. The surface soil is the uppermost layer of the soil profile, and the one we are most familiar with, because this is where most of the action takes place. Soil mixing with tillage, compost and fertilizer application, irrigation, plant root growth, and animal activity (including microbes) are mainly concentrated within the soil's surface layer. Additionally, decomposition of plant and leaf litter occurs most rapidly in the surface soil, this eventually leads to the formation of new soil organic matter. In comparison, the subsurface soil, or subsoil, is composed of one or more soil layers that lie below the influence of surface soil activities. There is not a consistent depth at which every surface soil layer changes into the subsoil layer(s), rather the subsoil occurs at a different depth from place to place depending on numerous factors, including some of the factors mentioned previously. This is the reason why it is difficult to determine where the subsoil layer begins in the soil profile.
What does subsoil contain?
What does subsoil look like?
What is subsoil used for?
In general, the subsoil is a less suitable medium for plant growth compared to surface soil because of some of the factors mentioned previously. There are properties of subsoil however that make it suitable for other uses such as a source of “fill soil” for “cut-and-fill” construction operations, as a source of clay for building materials, and as an absorption layer for on-site wastewater disposal.
What can home gardeners do to keep their subsoil in great shape year after year?
What is the substratum layer of soil? Does that layer affect gardening at all, and if so how?
What is the bedrock layer? Does that layer affect gardening at all, and if so how?
Bedrock is the bottom layer of the soil profile layer cake. The bedrock layer consists of solid rock that has not yet been exposed to the chemical, physical, and biological processes of the surface soil and subsoil. In some places, bedrock is the foundation from which the overlying soil layers developed, while in other places, the bedrock layer may have become “buried” by windblown sand or sediment. Bedrock does not directly influence plant growth, but it can determine the type of clay minerals found in different layers of the soil profile.
Dr. Anthony Fulford is the Area Nutrient Management and Soil Quality Advisor for Stanislaus, Merced, and San Joaquin Counties.
/h3>/h3>/h3>/h3>/h3>/h3>/h3>- Author: Anne E Schellman
The Benefits of Trees
Trees provide so much more than shade. Here are a few reasons trees are important, courtesy of the International Society of Arboriculture (ISA):
- Air-conditioning costs are lower in tree-shaded homes & businesses; heating costs are reduced.
- In workplaces with trees, people report decreased workplace stress and fatigue.
- Cleaner air: leaves filter the air we breathe by removing dust and other particles.
- Cooler environment: trees reduce heat in and around parking lots and paved areas.
Trees and the Drought
California residents are being asked to lower their water use by 15%. One easy way to do this is to turn off your sprinklers. But wait! What happens to the trees? Although they may look okay for now, the stress of going without water will take a toll. Lawns can be easily replanted and replaced, but trees take many years to become established.
What do Trees Need?
How Should I Water My Tree?
There is no “silver bullet” on how often or how much to water. This depends on many factors. Instead, after you water, take a shovel (away from tree roots) and check your soil. How deep did the water penetrate? Make sure water penetrates to a depth of 18” by digging with a shovel. Once that area is dry, water again.
Prioritize Watering Trees with the TRIC
For more information about the value of trees, visit the following resources.
Resources
California Center for Urban Horticulture. UC Davis. Tree Ring Irrigation Contraption. https://ccuh.ucdavis.edu/tric
International Society of Arboriculture (ISA). Trees are Good. https://www.treesaregood.org/Portals/0/TreesAreGood_Benefits%20of%20Trees_0321_1.pdf
Water Talk. Janet Hartin. Podcast Episode 21. https://water-talk.squarespace.com/episodes/episode-21
This article was originally published on July 26, 2021.
/h3>/h3>/h3>/h3>/h3>/h3>- Author: Ed Perry
- Editor: Anne Schellman
To have your soil analyzed, contact a commercial testing laboratory. For a list of soil laboratories located in Stanislaus, Merced, Fresno, and Merced Counties, visit https://cemerced.ucanr.edu/ClimateSmartAg/HSP/SoilTest/Soil_Testing_Laboratories_in_Fresno_Madera_Merced_and_Stanislaus_Counties/
Vegetable Gardens
For vegetable gardens, the application of a fertilizer containing nitrogen and phosphorus is usually all your soil will need to get your vegetables off to a strong start. Other nutrients like zinc or iron are sometimes deficient or unavailable in certain soils, but they are usually not applied unless plant deficiency symptoms appear.
Diagnosing a Plant Problem
Besides moisture, oxygen is also required in the soil for good root growth. Poorly drained soils often have little oxygen in them because excess water fills all the spaces between the soil particles. My advice to gardeners is to correct drainage problems first, then worry about fertilizers. Often problems with sick and dying plants are caused by overwatering or a lack of good soil drainage than by nutrient deficiencies.
If you have an unhealthy plant, gently dig near the root system and check soil moisture and drainage. Since plant roots need oxygen, roots may suffocate if excess water does not drain quickly. Unfavorable climatic conditions, including temperature extremes and drying winds can also affect plant growth, as well as insect pests and diseases. For small plants, pull up a plant or two and check to see if the roots are healthy.
The best way to keep soil healthy, especially in vegetable gardens is to add compost annually to improve soil health. For perennial crops like fruit trees, annual applications of fruit tree fertilizer in spring can be beneficial.
The UCCE Stanislaus County Master Gardeners Can Help!
If you need help diagnosing a plant problem, take a plant sample to the UCCE office located at 3800 Cornucopia Way Ste A in Modesto. Master Gardeners are available on Wednesdays from 9:00 a.m. to noon in person or by phone (209) 525-6802. You can drop off a sample anytime during business hours or fill out an online survey and attach photos using this link http://ucanr.edu/ask/ucmgstanislaus A Master Gardener will get back to you within 5 days of your request.
If you live in another county in California, you can find your local Master Gardener program by using this link https://mg.ucanr.edu/FindUs/
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.
/h4>/h4>/h4>- Author: Ed Perry
Container gardening is popular both for growing annual and perennial flowers, herbs and certain vegetables. When discussing the topic with gardeners, nearly everyone agrees that the best growing media to place in the container are the mostly organic potting soils readily available at retail nurseries and garden stores. However, some gardeners still insist on adding a layer of gravel or other coarse material in the bottom of the container in the belief that drainage will be improved. I recently came across an article entitled "The Myth of Drainage Material in Container Plantings," by Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor at Washington State University. According to Chalker-Scott, "This is just one of those myths that refuses to die, regardless of solid scientific evidence to the contrary."
Chalker-Scott writes that nearly every book or web site on container gardening recommends placing coarse material at the bottom of containers for drainage. The materials most often recommended for this practice are sand, gravel, pebbles, and pot shards. Some of these recommendations are quite specific and scientific sounding. To illustrate her point she refers to this piece of advice from a 1960's book on container plants: “Adequate drainage is secured by covering the hole in the bottom of the pot with a piece of broken flowerpot, concave side down; this in turn is covered with a layer (1/2" to 1" deep) of flowerpot chips. On top of this, a 1/4" to 3/8" layer of coarse organic material, such as flaky leaf mold, is placed.” The advice seems to make perfect sense, says Chalker-Scott, and it's presented so precisely. After all, we know that plants need good drainage, so their roots receive adequate oxygen, and we also know that water passes through coarsely textured material faster than it does fine material So, what's not to like?
Chalker-Scott then explains that nearly 100 years ago, soil scientists demonstrated that water does not move easily from layers of fine textured materials to layers of coarser textured materials. Since then, similar studies have produced the same results. Additionally, one study found that more moisture was retained in the soil underlain by gravel than that underlain by sand. Therefore, the coarser the underlying material, the more difficult it is for water to move across the interface. Imagine what happens in a container lined with pot shards! Chalker-Scott states that, despite popular belief, gravitational water will not move from a fine textured soil into a coarser soil until the finer soil is saturated. Roots suffocate in saturated soil, because water replaces oxygen in the soil pore spaces, and roots require oxygen. Concludes Chalker-Scott, since the stated goal for using coarse material in the bottoms of containers is to "keep soil from getting water logged," it is ironic that adding such material will do just the opposite. The bottom line: fill the container from bottom to top with a well-drained potting soil, and don't block the drain hole.
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.